1. Field of the Invention
This invention relates to row crop attachments for harvesting machines. The invention will be discussed in relation to forage harvesters but is not restricted thereto.
In the preparation of forage from "stalk" crops, such as corn and sorghum, the entire stalk, including the grain, is cut and fed to a chopping or cutter unit for chopping into small feed pieces. Forage harvesters for preparing forage in this way normally comprise a base unit having a chopping mechanism and a crop gathering unit which cuts the crop and conveys it to the chopping mechanism. The chopped or cut crop is blown, or otherwise conveyed, into a trailing wagon or the like in which it is transported to a silo or other storage facility.
2. Description of the Prior Art
Crop gathering attachments have been developed to cut one, two, three, or four rows of crops at one time. These gathering means comprise a mechanism for severing the stalks and delivering them, butt ends first, between opposed feed elements. Such gathering means also comprise a pair of laterally opposed gathering frames for each row of crop, the frames defining between them a stalk-receiving passage in advance of, and aligned with, the feed elements. Angularly disposed flights of gathering chains are usually provided along the gathering frames to insure that the stalks move rearwardly into the forage harvester and to hold the stalks in the required orientation until they are acted upon by the feed elements. The gathering frames customarily are provided with rearwardly and upwardly inclined fenders or surfaces over which the stalks may ride and be supported during their movement through the gathering means.
In the past a large number of moving parts have been incorporated in the crop gathering means. Usually two or more pairs of superposed gathering chains, and associated drive means, have been employed per row of crop handled by the harvester. Such a large number of moving parts not only requires a great amount of motive power but also increases the cost of manufacture, maintenance and operation. Also, the gathering chains, which are quite expensive, are fast-wearing components and it is not exceptional to have to replace all gathering chains at the end of every season and even replacement during the course of a season is sometimes necessary. Chain replacement is a time-consuming, cumbersome and expensive exercise. In addition, the large number of moving parts and their supporting structure result in a relatively heavy crop gathering attachment which is particularly undesirable in certain machines. For example, in some forage harvesters the crop gathering attachment used to harvest corn may be interchanged with other attachments, such as those used for picking up hay in windows or direct cutter units for grass. A heavy or bulky gathering unit increases the difficulty of attachment and detachment, and also of supporting and adjusting the gathering unit relative to the base unit. As the gathering attachments are attached to the forward end of the base unit, heavy attachments may result in an undesirable positioning of the center of gravity relative to the wheel base of the machine.
Despite the large number of crop-engaging components normally employed, some of the severed crop escapes the action of the conveying means and either becomes entangled in the various components and plugs the machine or falls to the ground and is a loss to the harvesting operation.
Other crop gathering attachments have only one pair of gathering chains per crop row. The height of such attachments is substantially smaller than the height of those described above and, therefore, these attachments are often identified as "low profile" attachments. The drive means in a "low profile" attachment are less complicated and comprise fewer components, whereby the cost thereof is also reduced accordingly. Unfortunately, such low profile attachments need to be moved much more accurately along the rows of crop, otherwise stalks frequently are missed by the gathering chains and thus lost. This requires the sustained attention of the operator which is tiring and can slow down the operation of the harvester. This problem is accentuated when harvesting corn which has been wholly or partially flattened by storms, or when harvesting tall crop. Also, severed stalks occasionally escape the grasp of the gathering chains and are lost. Furthermore, the low profile gathering attachments still have the expensive and fast-wearing gathering chains.
Gathering attachments without gathering chains are also known. Some of these attachments have a pair of opposed upright gathering rolls positioned forwardly of the conventional transverse feed rolls and at the rear ends of the crop gathering frames. Others have two pairs of opposed, vertical gathering rolls. The forwardmost gathering rolls have a pair of rotary cutting blades adjacent their lower ends for severing the stalks from the ground during operation, and both pairs of rolls operate to convey cut crop rearwardly of the forage harvester either to transverse pre-compression feed rolls or to the chopping unit disposed immediately rearwardly thereof. This type of gathering attachment has a limited harvesting capacity. Moreover, crop feeding problems frequently occur with such arrangements and therefore, this type of forage harvester attachment has, to date, not been acceptable.